In a labor stage of a pregnant woman, it is necessary to perform a further process according to an obtained fetal heart rate so as to realize clinical fetal monitoring. Because in the labor stage, uterine contraction of the pregnant woman makes fetal echo weak, accuracy of the obtained fetal heart rate is relatively low. Especially in a second stage of the labor, the uterine contraction of the pregnant woman is severe, and in a time interval when the uterine contraction occurs and a time interval after the uterine contraction, what a fetal heart probe has detected is pulse echo reflected from an abdominal artery or an umbilical artery of the pregnant woman. A result calculated according to the pulse echo is a pulse of the pregnant woman, which means that data output under this circumstance may be a fetal heart rate or a pulse rate of the pregnant woman. Furthermore, because in the second stage of the labor, the pregnant woman would move strenuously for the pain of the uterine contraction, the pulse rate the pregnant woman is generally high at this time; especially when the pulse rate of the pregnant woman is about 110 bpm, the pulse rate of the pregnant woman is prone to be misunderstood as the fetal heart rate, thereby resulting in that the obtained fetal heart rate is indeed invalid data.
In order to solve the above problem, the prior art generally adopts a photoelectric sensor built in a probe, which obtains a fetal heart rate and synchronously calculates the pulse rate of the pregnant woman according to light intensity received by the photoelectric sensor. Then the fetal heart rate and the pulse rate of the pregnant woman would be compared to determine whether the obtained fetal heart rate is valid data.
However, there exist the following deficiencies in the prior art:
the photoelectric sensor is prone to be affected by factors such as ambient light and movements of the pregnant woman, which may result in that the accuracy of the obtained pulse rate of the pregnant woman is low. During the uterine contraction of the pregnant woman, whether an accurate fetal heart rate is detected is especially important, however, the prior art generally cannot detect the pulse rate of the pregnant woman during uterine contraction;
Since the accuracy of the pulse rate of the pregnant woman obtained by the prior art is low, and under special conditions, such as uterine contraction, the pulse rate of the pregnant woman may be even unable to be obtained, when the fetal heart rate is compared with the pulse rate of the pregnant woman, and whether the obtained fetal heart rate is valid date is judged according to the comparison result, it may result in that the accuracy of the obtained fetal heart rate is low too. Therefore, the prior art is still unable to provide an effective determination criterion on whether the fetal heart rate is correct.